1. Field of the Invention
The present invention relates to a method of processing an organic film and a method of manufacturing a semiconductor device, in which a plasma etching is used.
2. Related Art
Dry etching which uses radicals generated by plasma discharge is widely used as a method of processing a semiconductor substrate or a method of processing various thin films formed on a semiconductor substrate.
In a case where a trench is formed in an organic film by using a protective film pattern disposed on the organic film as a mask, if plasma etching is performed using a gas which contains hydrogen as a main component, there arises the problem that a plasma causes not negligible damage to an underlayer film exposed to the bottom part of the trench of the organic film.
Particularly, with miniaturization and high integration of the semiconductor device, when a dielectric film having a smaller dielectric constant than that of a silicon oxide film is used as an underlayer film, the above-described damage may easily occur.
Plasma etching techniques which form trenches in a silicon substrate by using a gas which contains deuterium (D2) as a main component have hitherto been known. For example, see the Japanese Patent Laid-Open No. 6-84841 (page 2, FIG. 1).
In the plasma etching technique disclosed in the above patent document, trenches are formed in a silicon substrate by performing plasma etching using a silicon oxide film as a mask and using a gas which contains deuterium as a main component. In this technique, etching rates which are an order of magnitude higher than when hydrogen (H2) gas is used are obtained.
However, the above patent document discloses only an example in which a silicon substrate is etched by a gas which contains deuterium as a main component. Furthermore, it neither discloses nor suggests gases other than deuterium.